don't stop iteration if behaviour returns undefined

lib/ace/mode/text.js

@@ -206,13 +206,12 @@ var Mode = function() {
             for (var key in behaviours) {
                 if (behaviours[key][action]) {
                     var ret = behaviours[key][action].apply(this, arguments);
-                    if (ret !== false) {
+                    if (ret) {
                         return ret;
                     }
                 }
             }
         }
-        return false;
     }
     
 }).call(Mode.prototype);